Telegram (ask questions / claim the issue here first): https://t.me/+DOylgFv1jyJlNzM0

Why this matters

index.ts:32 calls sorobanIndexerService.start() AND index.ts:33 startWorkers() starts SorobanEventWorker; both poll STREAM_CONTRACT_ID and write Stream/StreamEvent. Both WITHDRAWN handlers READ-then-ADD withdrawnAmount (soroban-indexer.service.ts:216 and soroban-event-worker.ts:631) in separate transactions, so when both fetch the same new event before either commits, the increment is applied twice -> inflated withdrawnAmount -> wrong claimable. The legacy service also keeps cursor in-memory and ignores IndexerState.

Acceptance criteria

• Remove sorobanIndexerService.start()/stop() from index.ts so only SorobanEventWorker indexes events
• Delete or disable services/soroban-indexer.service.ts
• Add a regression test asserting only one indexer instance polls the contract
• Verify withdrawnAmount is not double-incremented when the same WITHDRAWN event is observed

Files to touch

• backend/src/index.ts
• backend/src/services/soroban-indexer.service.ts
• backend/src/workers/soroban-event-worker.ts

Out of scope

• Contract-side changes
• Frontend indexer status UI